The public aid is half what Cubs Chairman Tom Ricketts sought in 2010 when he first proposed using ticket taxes to pay for a major overhaul of baseball's second-oldest ballpark

To raise $150 million in revenue to help renovate Wrigley Field, the Cubs are considering several options, including more signs like the red Toyota logo behind the outfield bleachers. (Phil Velasquez, Chicago Tribune)

Mayor Rahm Emanuel wants to cut in half the amount of government support sought by the Chicago Cubs to renovate Wrigley Field, with the team picking up the rest of the $300 million tab, according to sources familiar with the negotiations.

Talks in recent weeks have focused on a public financing package worth $150 million backed by taxes the city and county collect on every ticket sold at Wrigley Field. The idea is that the Cubs would use the future gains in the tax to pay for the stadium's face-lift.

The public aid is half what Cubs Chairman Tom Ricketts sought in 2010 when he first proposed using ticket taxes to pay for a major overhaul of baseball's second-oldest ballpark. Emanuel, though, has said publicly that he is not willing to fully subsidize the renovations. But he didn't shut the door on tax money being used.

Under the mayor's framework, the team would be responsible for half the costs of the project. The trade-off, it appears, will lead to more commercialization of Wrigley Field that will change the look of the beloved icon.

To raise $150 million in revenue, the team is considering several options, sources said, including:

•More signs like the red Toyota logo behind the outfield bleachers.

•A Jumbotron.

•Selling concessions on streets around Wrigley.

The stadium changes would require accommodations, such as altering the city law that confers landmark status on Wrigley Field. The mayor is open to streamlining that process, which would make it easier for the Cubs to add more advertising around the ballpark, a source said.

Emanuel signaled as much in comments last week to reporters.

"The Ricketts family in 2009 made a decision to buy Wrigley Field and buy the Cubs. That was their decision," Emanuel said. "…The (Rickettses) purchased it, they have a responsibility that comes with it. We may make changes so they can enhance it."

The mayor's office is not discussing particulars of the negotiations.

"Conversations between the city, state, county and the Cubs organization have been productive and are still ongoing. There is no agreement at this time," said Emanuel spokeswoman Sarah Hamilton.

The negotiations about Wrigley Field underscore an age-old dilemma about the ballpark. It is a private asset, yet it is treated as a public treasure — a baseball shrine that should be preserved for future generations.

But as lovable as the 98-year-old ballpark is, even the most avid Cubs fan will admit that it lacks certain basic amenities, such as adequate entrances and exits, proper access for the disabled, wide concourses to ease congestion and modern restrooms and concession areas.

The previous owner, Tribune Co., parent of the Chicago Tribune, which retains a small stake in the Cubs, tried to address the problems over time, but significant changes to increase revenues, such as night games and bleacher expansion, came only after dealing with neighborhood and political opposition.

The landmark status, passed in 2004 as the Cubs were gearing up for a bleacher expansion, placed more limits on the team's control of its facility. The city law protects such familiar elements as the red marquee sign at Clark and Addison streets, the center-field scoreboard and the ivy-covered outfield walls.

It also safeguards the ballpark's overall contours, from the exposed steel columns and beams that frame its exterior walls to the uninterrupted "sweep" of the grandstand and bleachers.

Given the public constraints and the precedent for public financing for stadiums for the White Sox and Bears, the Ricketts family sought assistance for Wrigley's reconstruction. Their 2010 plan received support from some state legislators because of the ballpark's importance as a tourist mecca and economic engine. The proposal included the family investing $200 million in commercial development outside the stadium.

But a negative reaction from then-Mayor Richard Daley, who had already decided he wasn't running for re-election in 2011, doomed the Rickettses' proposal.

Tom Ricketts has continued to pursue a public-private partnership with Emanuel. But the mayor, a former investment banker, has sought some protections to minimize the risk of the investment for taxpayers.

Under the proposal, the city and Cook County would be guaranteed a certain level of ticket, or amusement, taxes each year. The exact amount is still being negotiated. The average amount of taxes in the past seven years generated from the 12 percent levy on Cubs tickets is $14.6 million, a source said. But amusement tax revenues fell last year and are expected to decline again in 2012, the source said.